In the field of laboratory tests, various analysis apparatuses such as blood cell counters, immunoassay apparatuses, blood coagulation analyzers, and biochemical analyzers are used depending on the desired measurement parameters. Thus, it is typically necessary to manage multiple analysis apparatuses. Moreover, it is typically necessary to collect multiple specimens from a patient depending on the parameters to be measured, which places a considerable burden on the patient. Consequently, an automated analyzer capable of analyzing multiple parameters in a single specimen would be desirable.
Blood cell counting involves differentiating blood cells contained in blood (i.e., whole blood) and counting according to blood cell type. The blood cells are generally differentiated into erythrocytes, leukocytes, platelets, and the like. Thus, erythrocyte number, leukocyte number, and platelet number are representative parameters of blood cell counting. In addition, reticulocytes which emerge in peripheral blood in an immature state of erythrocytes are differentiated and counted in some cases.
An analysis apparatus for blood cell counting includes an automated hematology analyzer, such as the XE-2100 supplied by Sysmex Corporation. Here, blood cells are stained with specific fluorescent dyes, optical information (e.g., forward scattered light, side scattered light and fluorescence) is detected from the respective blood cells by flow cytometry, and the blood cells are differentiated and counted by combining this optical information. In addition, this analysis apparatus has a counting function for reticulocytes, whereby forward scattered light intensity and side fluorescence intensity are detected from the fluorescently stained blood cells by reacting with staining solution without hemolysis. Two dimensional scattergrams are made using these as parameters to differentiate the blood cells into platelets, erythrocytes, reticulocytes and the like. The staining solution for fluorescent staining of the blood cells contains a dye which stains nucleic acid contained in the blood cells, and stains the leukocytes and reticulocytes. The side fluorescence intensity detected from the blood cells provides information indicative of the amount of nucleic acid in the blood cells, and the blood cells can be differentiated by combining the forward scattered light intensity (size information) and the side fluorescence intensity (nucleic acid amount information).
In addition to blood cell number, mean corpuscular volume (MCV) and hematocrit value are also used as parameters of blood cell counting. MCV is a mean value of erythrocyte sizes in whole blood. The hematocrit value is a percentage of blood cell component occupying the whole blood. Since an erythrocyte volume occupies a vast majority of the blood cell volume, the hematocrit value is calculated by measuring the erythrocyte number and MCV in the whole blood, multiplying the MCV by the erythrocyte number in the whole blood, and dividing it by the volume of the whole blood.
An immunoassay is an assay method for making an antigen or an antibody contained in a specimen (e.g., blood) a substance to be assayed, which is detected by taking advantage of an antigen antibody reaction. Representative immunoassays include an enzyme immunoassay (EIA) method, a radioimmunoassay (RIA) method, a particle agglutination method, and the like. The particle agglutination method is a method in which a substance to be immunoassayed is detected by blending carrier particles sensitized with an antibody or an antigen corresponding to the substance to be assayed with a sample, inducing a particle agglutination reaction due to the antigen antibody reaction, and measuring the degree of the particle agglutination (degree of agglutination) from changes in absorbance and light scatter.
In conventional particle agglutination methods, a sample containing carrier particles after the agglutination reaction is measured by flow cytometry and the degree of agglutination is obtained based on optical information obtained from the respective particles. When the information which reflects size of the carrier particles (e.g., forward scattered light) is used as the optical information, unagglutinated carrier particles can be discriminated from agglutinated carrier particles, and the degree of agglutination of the carrier particles can be obtained. A rate of agglutination method for determining degree of agglutination is described in JP-B-6-19349. In this method, scattered light intensities of respective particles are measured by a flow cytometer. Non-agglutinated single particles and agglutinated particles which occur by agglutinating multiple carrier particles are differentiated according to their respective scattered light intensities. Single particle number (M) and agglutinated particle number (P) are counted to obtain a total particle number (T) which is a sum of M and P, and P/T is calculated as the rate of agglutination. Since the reaction can be caught at a stage where two carrier particles are agglutinated, an extremely high sensitivity immunoassay becomes possible. In this rate of agglutination assay, various methods (e.g., in which the rate of agglutinated particles measured equals or exceeds a certain number) can be used depending on the assay level range of the substance to be immunoassayed. The rate of agglutination assay method in the above-described JP-B-6-19349 is used for the immunoagglutination assay apparatus PAMIA series supplied by Sysmex Corporation.
Whole blood, serum, plasma, and the like are used as samples in the above-described apparatuses for blood cell counting and immunoassay. However, while whole blood samples are typically used in the blood cell counter, serum or plasma are typically used in other apparatuses (e.g., the immunoassay apparatuses). A blood cell counting/immunoassay apparatus using whole blood in which blood cell counting and immunoassay can both be carried out is described in U.S. Pat. No. 6,106,778. This apparatus has a blood cell counting portion and an immunoassay portion, and measures by dispensing the whole blood sample into the blood cell counting portion and the immunoassay portion, respectively. In the immunoassay portion, the immunoassay is carried out by hemolysing the whole blood sample with a hemolytic agent and using latex reagents.
However, when both blood cell counting and immunoassay are to be performed, it would be highly desirable that the blood cell counting and the immunoassay be carried out in an identical measurement section in order to reduce the amount of specimen collected from a patient and to enable measurement by a single small analyzer.